Stevia rebaudiana is a plant species in the sunflower (Asteraceae) family, which has naturally sweet leaves. The active compounds that impart the sweet flavor to stevia leaves are steviol glycosides. The most common steviol glycosides are stevioside and rebaudioside A, both of which have up to 250 to 400 times the sweetness of sugar. Stevioside tends to be more prevalent in unimproved lines of stevia leaves than rebaudioside A. The development of new varieties of Stevia rebaudiana with higher levels of rebaudioside A than stevioside is desirable for use as a sugar substitute.
The present invention relates to a new and distinct variety of Stevia rebaudiana, the ‘SW 201’ line, which has very sweet leaves with high levels of steviol glycosides and very low bitterness and aftertaste, excellent overwintering, high plant vigor, high leaf yield, and late flowering.
The ‘SW 201’ line was derived in 2012 from a single plant in a population of recurrently selected Stevia rebaudiana, the population of which was originally grown from seed in an outdoor field in Chowchilla, Calif., USA, under natural lighting. The parentage of the ‘SW 201’ line is not known and population from which the ‘SW 201’ line was derived has no patented parental lineage. The plant that produced the ‘SW 201’ line was selected from its population based upon the following characteristics, which were measured and/or observed between 2012 and 2014.
Leaf Taste:
The leaves of the ‘SW 201’ line were found to have an excellent sweet taste in comparison to a majority of the plant population from which the line was derived and very little bitterness and aftertaste in comparison to most stevia varieties.
Overwintering:
The ‘SW 201’ line was found to have superior overwintering in comparison to the majority of the plant population from which the line was derived, the latter of which died over the course of the winter.
Plant Vigor:
The ‘SW 201’ line was found to have greater growth with higher leaf yield and later flowering (an advantage for leaf production) in comparison to the majority of the plant population from which the line was derived.
Steviol Glycosides:
The leaves of the ‘SW 201’ line were found to have high levels of steviol glycosides (over 18%) with rebaudioside A accounting for over 60% of the total steviol glycoside content in the leaves (see, Table 1).
Upon initial selection, the ‘SW 201’ line was asexually reproduced from rooted cuttings in May 2012. Plant yield and leaf quality of the ‘SW 201’ line were confirmed in April through October 2014 through replicated yield trials in the following three locations: Yuma, Ariz.; Indio, Calif.; and Ontario Oreg. At each of the three locations, the performance of the ‘SW 201’ line grown from cuttings was compared to seedlings of the ‘Candy’ line (Genesis Seed Ltd., Ashalin, Isreal; unpatented) grown from bulk commercial seed (“the check variety”). Table 1 compares various characteristics of an average sampling of leaves of the ‘SW 201’ line with an average sampling of leaves of the check variety.
TABLE 1SW 201Check VarietyPercentage of Rebaudioside A11.17% 6.85%Percentage of Stevioside 5.29% 6.42%Percentage of total Steviol18.04%14.71%GlycosidesRatio of Rebaudioside 2.19 1.11A: SteviosidePercentage of Rebaudioside A to 60.9%46.8%total Steviol Glycosides
The data in the foregoing table shows that in comparison to the check variety, the ‘SW 201’ line contained more rebaudioside A (11.17% vs. 6.85%); less stevioside (5.29 vs. 6.42%); more total steviol glycosides (18.04% vs. 14.71%); a higher rebaudioside A to stevioside ratio (2.19 vs. 1.11); and a higher percentage of rebaudioside A to total steviol glycosides (60.9% vs. 46.8%). In addition to the foregoing, the ‘SW 201’ line also produced 22% more leaf yield than the check variety with the ‘SW 201’ line producing 4,129 lb of leaf per acre per year versus 3,386 lb of leaf per acre per year for the check variety. Leaf yield results were averaged over three locations with four replications at each location, and two harvest strategies (one or two cuttings per year). The higher yield of the ‘SW 201’ line was due in part to low stand loss from Fusarium and other root diseases that reduced plant stand of the check variety.